The present invention relates to high precision measuring methods and apparatus, and particularly to a method and apparatus for measuring distance, temperature, and virtually any other parameter or condition having a known relation to, or influence on, the transit time of movement of an energy wave through a medium. The present invention is particularly useful in the method and apparatus described in the above cited U.S. Pat. No. 6,621,278, the contents of which are incorporated herein by reference; and the invention is therefore described below with respect to that method and apparatus.
As brought out in U.S. Pat. No. 6,621,278, many measuring techniques are known for measuring distance, temperature, and other parameters, but such known techniques generally increase in expense according to the precision desired, and also generally have an upper limit as to the precision practically attainable by the technique. For example, the measurement of distances of meters or kilometers with a precision of microns or fractions of a micron is extremely expensive, if attainable at all. The same limitations apply with respect to measuring temperature, force, and other conditions.